Chapter 12 (BIOL110)

Name the organs of the lymphatic system. 

The lymphatic vessels, lymphoid tissues, and organs

What is lymph? 

Excess tissue fluid that had entered the lymphatic capillaries, and fluid within the lymphatic vessels

What are the functions of lymphatic vessels? 

They collect the lymph and return it to the blood, and they form a one-way system flowing towards the heart

The right lymphatic duct collects lymph from the right upper extremity and the right side of the head and thorax, which drains into the right subclavian vein

The thoracic duct collects lymph from the rest of the body, and it drains into the left subclavian vein

What is the function of lymph nodes?  The spleen? The thymus? Tonsils? Peyer’s patches?

They filter the lymph before it is returned into the blood. They filter harmful materials such as bacteria, viruses, cancer cells, and cell debris

The spleen filters blood

The thymus produces lymphocytes in juveniles 

The tonsils produce lymphoid tissue around the pharynx

The Peyer patches are lymphoid tissues in the wall of the small intestine and appendix

What are the major differences between the innate and adaptive immune systems?

The innate (nonspecific) immune system is the mechanism that protects against a variety og invaders. It responds immediately to protect the body from foreign materials

The adaptive (specific) immune system is a specific defense that is required for each type of invader

Describe the 3 lines of defense used to protect the body from a pathogen

The body coverings are a physical barrier or the first line of defense; the specialized human cells and chemicals produced in the body are the second line of defense, the the body-specific defense system is the third line of defense

Describe the surface membrane barriers of the body.

The surface membrane barriers of the body are the intact skin and mucous membranes

Describe the cells and chemicals used by the innate defense system.

They use the natural killer cells, phagocytes, complement proteins, interferon, and neutrophils

Describe the events of the inflammatory response.

They are triggered when the body tissue is injured. The four most common indicators of inflammation are redness, heat, swelling, and pain

What causes the cardinal signs of inflammation (redness, heat, swelling, pain)?

The neutrophils migrate to the injured area by chemotaxis, neutrophils squeeze through the capillary walls by diapedesis, and neutrophils phagocytose any foreign material

What is the function of the inflammatory response? 

They prevent the spread of damaging agents, they dispose of cell debris and pathogens through phagocytosis, and they set the stage for repair

Describe the 3 aspects of the adaptive defense portion of the immune system

Antigen-specific - they recognize and act against particular foreign substances 

Systemic - response not restricted to the initial infection site 

Memory - recognizes and mounts a stronger attack against previously encountered pathogens

What is the difference between cellular and humoral immunity?  

Humoral immunity provides antibodies present in body fluids, and antibody-mediated immunity

Cellular immunity targets virus-infected cells, cancer cells, and cells of foreign grafts, and cell-mediated immunity

What are antigens?

Antigens are any substance capable of stimulating an immune response

Some antigens are non-self proteins, nucleic acids, large carbohydrates, some lipids, pollen grains, and microorganisms

Name the two categories of lymphocytes.

Lymphocytes respond to specific antigens

• The two categories of lymphocytes are B Lymphocytes (B cells)  and T Lymphocytes (T cells)

• B cells = humoral immunity

• T cells = cell-mediated immunity

What is the function of antigen-presenting cells?  Name a few APCs.

They help activate lymphocytes, but do not respond to specific antigens. They engulf antigens and then present antigen fragments on their membrane surface.

Presented foreign antigens can be recognized by T cells, and T cells bind to presented antigens and are activated

Some APCs are dendritic cells, macrophages, and B lymphocytes

What is clonal expansion? 

When B cells undergo mitosis, producing a large number of B cell clones

What is the function of memory cells? 

They produce a rapid immune response against the same antigen in subsequent exposure 

Describe the structure of an antibody. 

4 polypeptide chains for a Y-shaped molecule, each polypeptide chain has a variable and a constant region, variable regions form antigen-binding sites, and one on each arm of the Y, constant regions determine antibody function and class 

Name the 5 major categories of antibodies.  State the function of each. 

IgM - can fix complement proteins

IgA - protects mucosal surfaces

IgD - important in the activation of B cells

IgG - can cross the placental barrier and fix complement (most abundant)

IgE - involved in allergies

What is the difference between a primary and secondary immune response? 

Primary hormonal response only occurs when a person is exposed to a specific antigen for the first time

Secondary hormonal response occurs when a person is exposed to the same antigen again

Name and describe the 4 types of acquired immunity. 

Active Natural - acquired during bacterial and viral infections

Active Artificial - acquired from vaccines

Passive Natural - acquired from a mother from her fetus

Passive Artificial - acquired from immune serum or gamma globulins

How do antibodies help fight against an infection? 

By Neutralization, Agglutination, Precipitation, and Complement Fixation

What are the functions of helper T cells? 

They recruit other cells to fight invaders, they interact diferly with B cells bound to an antigen, they release cytokines, chemicals that enhance the killing activity of macrophages, they attract other leukocytes into the area, they stimulate B cells and cytotoxic T cells to grow and divide

What are the functions of cytotoxic T cells?

They specialise in killing infected cells, and they insert perforin molecules into the membrane of abnormal or foreign cells

What are perforins and granzymes?

Perforins are pore-forming proteins, and granzymes are proteases that work together to kill target cells

What is the function of regulatory T cells?

They release chemicals to suppress the activity of T and B cells, and they stop the immune response to prevent uncontrolled activity

Describe the interaction between B cells and helper T cells. 

A two-way process where antigen-specific B cells present antigen to helper T cells, which then provide help for B cell activation, proliferation, and differentiation

What is the function of a B cell? Plasma cells? 

B cells differentiate into plasma cells as they produce antibodies to destroy antigens, and some B cells become long-lived memory cells that produce a rapid immune response against the same antigen in subsequent exposure